29 Oct 2014

How to calculate areas, part 2

Knowing how to calculate areas is an important task when planning your DIY or building project


Last time we discussed how to calculate areas of basic shapes, the square, the rectangle, the triangle and the circle. Click here to read part 1.


When planning your building or DIY project it is likely that your area does not consist of a single basic shape.

For instance, suppose we want to know the area of a gable end (Fig. 1) before cladding it in cedar shiplap or rebated feather edge.



One method to calculate the area is to divide the shape into components that are either triangular and/or rectangular. Next calculate the area of each component then add the sum of these areas to give your total area.



In Figure 2 we divide the gable end of the building into the rectangle, A, and the triangle, B. The total area is the sum of the two areas A and B. Giving the formula.


Total area  =  A + B  =  ( a x h1 ) + ½ ( a x h2 )




For instance, using dimensions a = 3.0m, h1 = 2.4m and h2 = 1.8m (Fig. 3), we obtain,


Area A  =  3.0 x 2.4  =  7.2 m2

Area B  =  ½ (3.0 x 1.8 )  =  2.7 m2

Total Area  =  A + B + 7.2 + 2.7  =  9.9 m2




We can expand this method further to calculate more complicated areas. Suppose we want to know the total area of the walls of a shed so we can calculate how much cedar TGV we require to clad the shed, see Fig. 4.  We calculate the area of each wall, A. B. C and D then add these areas together. In this example.,


Total Area  =  A  +  B  +  C  +  D




We now know the right formulas and a method to calculate area easily. This will help us calculate accurately the amount of product you require to complete your DIY and building projects.

If you prefer to not perform these calculations yourself, our experienced and knowledgeable staff are always on hand to help and advise you.


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